1. Field of the Invention
The present invention relates to a display apparatus employing an organic EL element.
2. Description of the Related Art
The organic EL element is constituted by laminating a first electrode disposed at a substrate side, an organic compound layer containing a light emitting layer, and a second electrode. Mentioned as the goal to be achieved of the display apparatus employing the organic EL element is a reduction in power consumption, and an improvement of the light emission efficiency of the organic EL element has been demanded.
To achieve the goal, Japanese Patent Laid-Open No. 2003-109775 describes an attempt of improving the current efficiency by introducing a resonator structure in which metals are used for both the first electrode and the second electrode. Moreover, in Japanese Patent Laid-Open No. 2004-039500, by disposing a lens at the light emission sides of all of the organic EL elements, light confined in the organic EL elements is extracted into the air and is condensed to the front to thereby improve the current efficiency.
In general, the reflectance of a metal thin film becomes small in a short wavelength of a visible light region as illustrated in FIG. 2. Therefore, when a metal thin film is used as an electrode at the light emission side in a display apparatus having organic EL elements which emit blue color, green color, and red color, the resonance effect of the organic EL element which emits blue color becomes smaller than that of the organic EL elements which emit other colors. As a result, when introducing the resonator structure as in Japanese Patent Laid-Open No. 2003-109775, the current efficiency of the organic EL element which emits blue color becomes more difficult to improve than the organic EL elements which emit other colors. Therefore, there is a problem in that the power consumption of the entire display apparatus does not decrease.
When a lens is provided as in Japanese Patent Laid-Open No. 2004-039500, there is a problem in that external light is scattered on the lens surface and oblique incident light is reflected to the front by the lens, so that the contrast decreases.